Start-stop telegraph system



Nov. 5, 1935. R. F. DIRKES ET AL 2,019,847

START-STOP TELEGRAPH SYSTEM Filed April 18, I954 2 Sheets-Sheet 1 III!|H'-'r TI l l l l l l 'l5l PIC-3.3

INVENTORS R.F.DIRKES Y E. R. WHEELER ATT NEY Nov. 5, 1935. R. F. DIRKESET AL 2,019,347

START-STOP TELEGRAPH SYSTEM Filed April 18, 1954 2 Sheets-Sheet 2 MLFIG. 4

T! A 1 l 3 4 l 5 I l BY q E. R. WHEELER Patented Nov. 5, 1935 PATENTOFFICE 2,019,847 START-STOP TELEGRAPH SYSTEM Robert F. Dirkes, Jamaica,N. Y and Evan E.

Wheeler, P

lainileld, N. L,

assiznors to The Western Union Telegraph Company. New York, N. Y., acorporation or New flesh Application April 13, 1936, Serial No. 721,206

10 Claims.

This invention relates to a start-stop system of telegraphy and moreparticularly to transmitting apparatus for such systems.

The primary object of the invention is to facilitate the maintenance ofphase relation between the transmitting apparatus and receivingapparatus.

In start-stop systems or telegraphy the signals consist of a startimpulse, a number of code impulses, usually five or six, and a restimpulse.

The receiving apparatus is started into operation by the start impulseand comes to rest during the rest impulse. Obviously, if the receivingand transmitting shafts are operating at the 5 same speed, with thetransmitting shaft continuously rotating, the receiving shaft will notactually stop' between signals, the succeeding start impulse beingreceived to restart the receiving shaft just at the instant it wouldnormally come to rest. However, such exactitude of synchronisrn betweenthe receiving and transmitting shafts cannot be maintained and shouldthe transmitting shaft have a slightly faster speed, it is obvious thatthe receiving shaft would not have completed its previous revolutionupon receipt of the next start impulse and consequently during thesucceeding revolutions the receiving elements would be out of phase withthe signals, and the printer would fail to correctly record the trans- 0mitted signals.

' The specific object of the present invention is to avoid this dimcultyand. insure that the start V impulse of one signal group is not receiveduntil the receiving shaft has completed its previous 35 revolution.

This object is accomplished in accordance with our invention bydefinitely stopping the transmitting shaft after each revolution andholding it at rest for a suflicient period to insure the com- 40 pleterotation of the receiving shaft, under all normal speed variationslikely to occur therebetween.

The invention will be best understood by reference to the accompanyingdrawings in which:

45 Fig. l is a side elevation of a keyboard transmltter embodying ourinvention;

Fig. 1A shows diagrammatically, the arrangement of the transmittingcontacts;

Fig. 2 is a vertical sectional view substantially 50 on the line 2-2 ofFigure l, with some parts omitted for the sake of clarity;

Fig. 3 is a timing diagram of the transmitting apparatus;

Fig. dis a diagrammaticview of a modified 5o embodiment of theinvention; and

Fig. 5 is a timing diagram of the transmitter shown in Figure 4..

Referring first to Figures 1 and 2, we have shown a keyboard transmittercomprising a bank of key bars l0, adapted when depressed to engage agroup of six notched code bars H to shift the same'in variouscombinations to set up, on the contacts of the transmitter, the varioussignal combinations. Cooperating with the code bars I l are individualpivoted locking latches l2 adapted to engage over the free ends ofcorresponding pivoted contact levers. Seven such levers are provided,the foremost lever It being the startstop lever and the remaining sixlevers l5 to 20 being the code levers. The latches 1! correspond only tothe code levers.

The seven contact levers control seven transmitting contacts ti, each ofwhich comprises a vertical spring '22 pressing against the inside of thehooked ends of the contact levers.

Disposed above the horizontal arms of levers id to 2B is the trattingshaft 23 upon which are mounted cams 25, one for each lever. Each camhas a depression 25 therein, arranged so that as the cam shaft rotatesthe depressions are 25 brought successively into position over a raisedportion 2t oi each lever. If at this time the levers are unrestrained bylatches it, they are tree to rock about their pivotsunder the action ofspring contact arm 22, to thereby close the corresponding contact 2 l IThe cam shaft 23 is driven from a motor shaft ill through a clutch 28normally held disengaged by a stop lever is pivoted at St. The lower endof lever 29 is-held in the path of a cam sleeve ti on the shaft 23, by aspring 32 and by camming action therewith, holds the clutch faces apartagainst the pressure of spring 33.

Located above the shaft 23 is a timing shaft 34,

driven through a start stop clutch 35 and gears 3%, ill, and 38, frommotor shaft ii. The clutch as is normally held disengaged by a stoparmis pivoted at til and having an inturned end engaging a cam sleeve ll onthe driven element of the clutch, to hold the clutch faces apart againstspring at. The stop arm 39 has a horizontal extension dS disposed so asto be engaged by a pivoted latch dd, the lower end of which is arrangedto be engaged by a trip lever 35, by movemerit thereof to the left. Thelever is secured to the vertical extension of a universal ball 66extending beneath the key levers l0.

Secured on the timing shaft is is a cam 41 having a depression 58disposed so as to receive 55 a projection on stop lever tion of thetiming shaft.

The operation of the mechanism is as follows: Assume the transmittingshaft 23 to have a speed of rotation approximately the sameas the shaftof the receiving equipment and shaft 34 to have a somewhat slower speed.For instance shaft 23 23, once each revolumay rotate at about 420 R.PLM. and shaft 34 may rotate at about 390 R. P. M. With the transmitterat rest, that is, with clutches 28 and 35 disengaged, the cam shaft 23will be in position to cause the start-stop contacts 2|s (Fig. 1A) to beclosed and a marking or rest condition will be sent over the line,thereby maintaining the receiving apparatus at rest.

Upon depression of a key In, the locking latches I 2 are positioned toset up a code combination on contacts .l5 to 20. At the same time theuniversal ball is rocked to draw trip lever 45 to the left, therebyrocking latch 44 to engage stop arm 39 and move its upper inturned endradially away from the cam sleeve 4|. Clutch 35 is thereupon engagedcausing timing shaft 34 to make a single revolution, the shaft beingstopped at the end of the revolution byre-engagement of stop arm 39 withcam sleeve 4| After cam 41 has rotated a short distance 'the depression48 comes opposite lever 29 and permits the same to be rocked by spring32 out of engagement with cam sleeve 3|, permitting clutch 28 to engageand starting shaft 23 into rotation.

As shaft 23 starts to rotate, the start-stop contact 21s is first openedto send a spacing or start condition to line, after which code contacts2la to 2|) (Fig. 1A) are closed in succession, unless held open bylatches l2, to send the code combination to line. Shaft 23 comes to restwith the start-stop contact'2ls again closed to apply a rest conditionto the line. The starting of shaft 23 is so delayed relative to thestarting of timing shaft 34 and the relative speeds of the two shafts,that both complete their revolution at substantially the same instant.However, since shaft 23 does not start again until shaft 34 has rotatedover a suflicient portion of the next revolution to bring cam depression48 again opposite stop lever 29, there will always be a lag in thestarting of the transmitting cam shaft. In the example assumed the shaft23 is at rest approximately 8 percent of each cycle. This has been foundsufficient in practice to insure that the receiving cam will have cometo rest before the next transmitting cycle is started. The usualkeyboard interlock (notshown) maybe provided to guard against depressionof another key before the combination has been completely transmitted.

The timing of the transmitter will be clear from an inspection of Figure3. In this figure (t) represents the time required for the timing shaft34 to make one revolution. A short time, (t) aftershaft 34 starts, shaft23 is released, transmitting a start impulse S, six code impulses I to 6and a rest impulse R during the period n, which is equal to (t-t) Thetime (t') represents the period of rest of the transmitting shaft.

I Reference will now be had to Figure 4 for a description of a modifiedembodiment of the invention. In this form of the invention, thestartstop cam 24 is placed on the cam shaft 23' so that the depressiontherein is ofiset slightly to one side of the hump of the correspondinglever I4, when the shaft is at rest, thereby normally retaining thestart-stop contact 2|s, open. The remaining cams 24", in place of havingdepressions therein, have a single raised portion 5|, the raised portionof each cam being in engagement with the corresponding contact levers l5to l9 inthe rest portion of shaft 23" to hold the code contacts 2Ia to2|f open.

The start-stop contact is connected through the start magnet 52 of arotary transmitting distributor TD and the code contacts 2m to 2!] areconnected to segments I to 6 of the segmented ring 53 of saiddistributor. This ring also has a rest segment R connected to batteryand a start segment S free from applied potential. The solid ring 54 isconnected to the outgoing line L.

The brush arm B of the distributor is normally held at rest on segment Rby a latch 55.

The line L terminates in the selecting magnet 56 of any desired type ofreceiver, having a receiving shaft 51, adapted to be driven at the samespeed as the brush arm shaft 58, say 420 R. P. M. Shaft 23' is driven ata somewhat lower speed, say 390 R. P. M.

The operation is as follows: With shaft 23' at rest, the start-stopcontact controlled by lever I4 is open and brush B is at rest on segmentR, with a rest condition applied to line L thereby holding shaft 56 ofthe receiving printer at rest. When a key I0 is depressed to set up aselection in levers I5 to shaft 23 is released for rotation by theuniversal bail in the usual manner. Immediately thereafter the drop ofcam 24' comes opposite lever l4 causing the associated contact to close,thereby energizing magnet 52 to release brush B for a. revolution. Atthe sametime earns 24" rotate to release simultaneously the levers l5 to20' and set up the selective signal on the segments of the face plate.As brush B rotates on to segment S, a start signal goes over the linereleasing the receiving shaft 51, which then rotates in phase with thebrush B. Brush B rotates faster than shaft 23' and completes itsrevolution somewhat ahead thereof, coming to rest at the same time asrecei'ving shaft 51. Brush B cannot be restarted for another revolution,however, until shaft 23' has completed its revolution and been releasedfor its next revolution, thereby insuring. the transmitting brush armshaft remaining at rest a predetermined minimum period between eachcharacter transmitted.

. 60 In the timing diagram shown in Figure 5, (t)

represents the time of revolution of cam shaft 23 and t1 the time ofrevolution of the brush arm shaft 58. Almost immediately upon release ofshaft 23', the start-stop contact closes releasing the brush arm shaft58. Shafts 23 and- 58 therefore start into rotation in close succession,as indicated at points of time A and A in Figure 5. The start-stopcontacts remain closed until point C is reached. The code contactscontrolled by levers l5 to 20' close at point B remaining closed untilpoint D is reached, at which time all the code 2m to ,2lf contacts openand remain open until point B is again reached, during the succeedingrevolution.

It will be noted, therefore, in each embodiment shown, that thetransmitting shaft is designed to rotate at the same speed as thereceiving shaft, but is held at rest for at least a predeterminedminimum period between each revolution, the duration of which dependsupon the difference in speed of the transmitting shaft and the slowerspeed timing shaft 34 in Figure 1 or the cam shaft 23' in Figure 4. Thisidle period of the transmitting shaft insures the receiving shaftaoiaeav coming to rest before the succeeding group of signals is begun.

Obviously variations of these embodiments will occur to those skilled inthis art and, therefore, we do not desire to be limited to theparticular details shown and described.

What we claim is:

1. In a start-stop telegraph system, -atransmitting cam shaft operableat a predetermined er speed, a keyboard mechanism for setting up codecombinations, means for releasing said second shaft for a singlerevolution on each actuation of said keyboard mechanism and meanscontrolled by said second shaft on each revolution thereof for releasingsaid first shaft for a single revolution whereby to transmit the codecombination set up by said keyboard mecha- 3. In a start-stop telegraphtransmitter, a driving member, a tratting shaft driven thereby, a timingshaft driven by said driving member at a slower rate than saidtransmitting shaft, single revolution clutches for each of said shafts,permutation means for setting up code combinations for transmission,means for releasing said timing shaft for a revolution for each codecombination set up, said timing shaft during said revolution releasingthe transmitting shaft for a single revolution to transmit the codecombination set up by said permutation means.

i. In a start-stop telegraph transmitter, a pair of elements eachmovable through a predetermined cycle for each character codecombination transmitted, said elements completing their cycles indifierent intervals of time, means for transmitting start, code and restimpulses over a period of time substantially equal to the length of thecycle of longest duration, said start and code impulses beingtransmitted over-a period substantially equal in length to the length ofthe cycle of shortest duration.

5. In a start-stop telegraph transmitter, a pair of elements eachmovable through a predetermined cycle for each character codecombination transmitted, one oi. said elements controlling the period oftransmission of the start and code impulses and the other elementcontrolling .he period of transmission of the rest impulse.

6. In a start-stop telegraph transmitter, a pair of elements eachmovable through a predeter mined cycle for each character codecombination cam shaft operable at substantially the same transmitted,means for starting said elements in movement at substantially the sametime and for stoppin each element at a different time, means fortransmitting start and code impulses during the time of simultaneousmovement of 5 both elements and means for transmitting a rest impulseduring the differential inthe time of stopping in each element.

7. In a start-stop telegraph transmitter, a pair of elements eachmovable through a predetermined cycle for each character codecombination transmitted, said elements both moving through at least apart of their cycles during a common time interval, one of said elementsbeing movable through another part of its cycle during a. separate timeinterval, means for transmitting start and code impulses during saidcommon time interval and means for transmitting a rest condition duringsaid separate time interval.

8. In a start-stop telegraph transmitter, a pair of elements eachmovable through a predetermined cycle for each character codecombination transmitted, means for starting said elements into movementin succession and means for transmitting a rest condition during theinterval be- 5 tween the starting of one element and the starting of theother element.

9. In a start-stop telegraph system,.a plurality of contacts comprisinga code contact for each element of the code and a rest contact, atransmitting cam shaft operable at a predetermined speed, a receivinginstrument having a selecting speed as said transmitting shaft, saidtransmitting shaft when at rest actuating said rest contact to transmita rest condition to said receiv-' ing instrument and when in rotation toactuate said code contacts in succession to transmit aseries of codeimpulses to said receiving instrument and means for retaining saidtransmitting 4O cam shaft at rest for at least a predetermined periodbetween each revolution thereof whereby a rest impulse of at least apredetermined duration will be invariably transmitted.

10. In a start-stop telegraph transmitter, a rotary distributor havingindividual contacts for each element of the code and a rest contact, akeyboard mechanism operable to set up code combinations on saiddistributor, a motor driven shaft released upon each operation of saidkeyboard mechanism for predetermined rotation, said shaft serving torelease said rotary distributor to transmit the code combination set upby said keyboard mechanism and to maintain the same at rest for at leasta predetermined period between the transmission of each character codecombination.

ROBERT F. DIRKES. EVANR. -WHEELER. so

